Cynthia Phua Siok Gek (Chinese: 潘惜玉; pinyin: Pān Xī Yù; Pe̍h-ōe-jī: Phoaⁿ Sioh-gio̍k, born 19 August 1958) is a former Singaporean Member of Parliament who has represented Aljunied GRC from 2001 to 2011.
In the 2011 general elections, she was part of a team of five candidates for the People's Action Party (PAP) which lost Aljunied Group Representation Constituency to the Workers' Party of Singapore (WP). Of the 143,148 registered voters in Aljunied GRC, 72,165 (54.7 per cent) voted for the WP while 59,732 (45.3 per cent) chose the PAP.